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https://github.com/Start9Labs/start-os.git
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57 lines
2.4 KiB
Bash
Executable File
57 lines
2.4 KiB
Bash
Executable File
#!/bin/bash
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if [ -z "$sip" ] || [ -z "$dip" ] || [ -z "$dprefix" ] || [ -z "$sport" ] || [ -z "$dport" ]; then
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>&2 echo 'missing required env var'
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exit 1
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fi
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NAME="F$(echo "$sip:$sport -> $dip/$dprefix:$dport ${src_subnet:-any}" | sha256sum | head -c 15)"
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for kind in INPUT FORWARD ACCEPT; do
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if ! iptables -C $kind -j "${NAME}_${kind}" 2> /dev/null; then
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iptables -N "${NAME}_${kind}" 2> /dev/null
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iptables -A $kind -j "${NAME}_${kind}"
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fi
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done
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for kind in PREROUTING OUTPUT; do
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if ! iptables -t nat -C $kind -j "${NAME}_${kind}" 2> /dev/null; then
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iptables -t nat -N "${NAME}_${kind}" 2> /dev/null
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iptables -t nat -A $kind -j "${NAME}_${kind}"
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fi
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done
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err=0
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trap 'err=1' ERR
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for kind in INPUT FORWARD ACCEPT; do
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iptables -F "${NAME}_${kind}" 2> /dev/null
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done
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for kind in PREROUTING OUTPUT; do
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iptables -t nat -F "${NAME}_${kind}" 2> /dev/null
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done
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if [ "$UNDO" = 1 ]; then
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conntrack -D -p tcp -d $sip --dport $sport || true # conntrack returns exit 1 if no connections are active
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conntrack -D -p udp -d $sip --dport $sport || true # conntrack returns exit 1 if no connections are active
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exit $err
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fi
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# DNAT: rewrite destination for incoming packets (external traffic)
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# When src_subnet is set, only forward traffic from that subnet (private forwards)
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if [ -n "$src_subnet" ]; then
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iptables -t nat -A ${NAME}_PREROUTING -s "$src_subnet" -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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iptables -t nat -A ${NAME}_PREROUTING -s "$src_subnet" -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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else
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iptables -t nat -A ${NAME}_PREROUTING -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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iptables -t nat -A ${NAME}_PREROUTING -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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fi
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# DNAT: rewrite destination for locally-originated packets (hairpin from host itself)
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iptables -t nat -A ${NAME}_OUTPUT -d "$sip" -p tcp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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iptables -t nat -A ${NAME}_OUTPUT -d "$sip" -p udp --dport "$sport" -j DNAT --to-destination "$dip:$dport"
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# Allow new connections to be forwarded to the destination
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iptables -A ${NAME}_FORWARD -d $dip -p tcp --dport $dport -m state --state NEW -j ACCEPT
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iptables -A ${NAME}_FORWARD -d $dip -p udp --dport $dport -m state --state NEW -j ACCEPT
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exit $err
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